The overarching goal of this proposal is to engineer novel, multifunctional drug and gene delivery systems that can target therapies to particular cells and intracellular compartments and also monitor delivery and determine therapeutic efficacy through the integration of advanced imaging technologies. To pursue this goal, this multi-PI application proposes to leverage existing strengths within UVA including: expertise in using advanced biomedical imaging techniques to assess ischemic heart disease in animal models and re-engineering recombinant adeno-associated vectors (rAAV) (French), screening molecular libraries in vivo to identify specific peptides capable of targeting diseased tissue (Kelly) so that the capsid surface displays specific peptides capable of targeting gene delivery to diseased tissue (Dasa). Not only will the targeting peptides validated during this project be used to develop a novel AAV-based cardiac gene delivery system, future applications include labeling the cardiotropic peptides with fluorophores and/or radiotracers to create contrast agents for the molecular imaging of ischemic heart disease. Similarly, the same cardiotropic peptides may prove valuable in targeting novel therapeutic agents directly to the heart after intravenous (iv) injection. In preliminary studies, the two PIs have already demonstrated the robustness and utility of the interdisciplinary technologies needed to achieve the following specific aims: 1) Validate additional peptides specific for the infarct border zone by evaluating their specificity with in vivo optical imaging and ex vivo confocal microscopy. 2) Optimize the cardiac gene delivery system by grafting cardiotropic peptide ligands into the AAV9 capsid for the selective delivery of expression cassettes driven by a cardiac-specific promoter. 3) Demonstrate the utility of the cardiac-targeted AAV gene delivery system by overexpressing the TTK protein kinase and down-regulating Meis1 transcription factor in the heart after myocardial infarction, then use advanced imaging techniques to quantify the therapeutic effect on LV remodeling. The development of this cardiac-targeted gene delivery system will establish a foundation for future research efforts including the engineering and evaluation of cardiac-targeted nanoparticles and liposomes as multifunctional platforms to facilitate not only the molecular imaging of ischemic heart disease, but also the targeted delivery of novel small molecule therapies. This proposal takes a multidisciplinary approach that makes extensive use of biomedical imaging, thus spanning the fields of radiology, cardiology, molecular imaging and molecular virology. The combined research/development project will result in: a) new targeting peptides that interact specifically with cardiomyocytes in vivo, b) new AAV-based systems for cardiac gene delivery with considerable potential for both pre-clinical research and translation to clinical applications, c) insights into the mechanism(s) of action for a novel gene therapy with clear potential for translational medicine.